Honeywell ST699 wired incorrectly?

[RandomGrinch]

Thanks, just searched for hive receiver and that does seem to be a British Gas supplied hive receiver. No idea where the thermostat control would be though. I do wonder if it got removed before we moved in.
Our plumber is coming tomorrow to service the boiler so I think we will get him to come in and see what he thinks.

Just in case you were interested, there is a very good video from @flameport simply explaining the 'S Plan' system:

Also attached is the installation manual for the ST699, including some example set ups.

Let us know how you get on with the plumber!

EDIT:
Hive receiver LED's
Status LED: Solid amber - receiver has paused it's search for devices - maybe the thermostat went with the move?
Central Heating LED: Solid green - Heating is on

 

[Rob Watt]

So we were definitely missing a thermostat. That's now been replaced and is connected but we still have the issue of the water needing to be on heat to get the heating to come on.
I'm sure I can work it out so will be working through the manual this weekend. Thanks.